CLAS physics database search results Measurement E151M1284 EG4 Xiaochao Zheng 2016 cos(theta_pi+) phi(pi+) A_LL Stat. error Syst. error degrees 0.55 234 -0.4531 0.7722 0.0593 0.55 246 -0.6294 0.7139 0.0771 0.55 258 -0.2657 0.7204 0.0424 0.65 222 -0.3298 0.7557 0.0478 0.65 234 -0.0927 0.5799 0.0318 0.65 246 -1.0216 0.5876 0.1191 0.65 258 0.9771 0.572 0.1142 0.75 162 0.2878 0.7712 0.0442 0.75 234 0.9495 0.6073 0.1112 0.75 246 0.2941 0.6198 0.0447 0.75 258 -1.3956 0.6033 0.1602 0.85 222 0.6985 0.7425 0.0843 0.85 234 -0.8173 0.6249 0.0969 0.85 246 -0.6714 0.6809 0.0815 0.85 258 0.489 0.5688 0.0628